Definition of the NADH dehydrogenase activity on plasma membranes from mouse liver and red blood cells. The kinetic properties, inhibitor sensitivity, hormone response and acceptor specificity will be determined for three types of plasma membrane dehydrogenase. Oriented membrane vesicles from erythrocytes will be used to determine the activity of the internal, transmembranous and external NADH dehydrogenase. The insulin sensitive dehydrogenase is expected to be the transmembrane dehydrogenase. Extraction and purification of the dehydrogenases with detergent treatment and sephadex columns will be carried out to determine how many components are involved. Analysis of flavin, iron, copper and molybdenum content of the membrane and the dehydrogenases as well as cytochrome determinations will indicate functional components. Conditions which control maximum response to insulin and other hormones will also be studied.